Operating element for motor vehicle components

ABSTRACT

The invention relates to an operator control element for motor vehicles having a fixed base body ( 1 ), a handle ( 3 ) which is mounted so as to be capable of rotating about an axis ( 2 ) in the base body ( 1 ), display windows ( 10 ) which are arranged radially around the axis ( 2 ), and an illumination device for illuminating at least one of the display windows ( 10 ). The invention provides that the illumination device has a plurality of light sources ( 7 ) which are arranged radially around the axis ( 2 ) of the handle ( 3 ) on the fixed base body ( 1 ) and can be switched individually, a lightguide element ( 5 ) is permanently connected to the handle ( 3 ) and has a light input face, which is successively moved past the light sources ( 7 ) when the handle ( 3 ) rotates, and a light output face, which is assigned to a photosensitive element ( 8 ). The photosensitive element ( 8 ) is connected to an electronic circuit ( 9 ) for evaluating the output signal of the photosensitive element ( 8 ), it being possible to determine a rotary position of the handle ( 3 ) by successively switching the light sources ( 7 ) and evaluating the output signal of the photosensitive element ( 8 ).

The invention relates to an operator control element for motor vehicleshaving a fixed base body, a handle which is mounted so as to be capableof rotating about an axis in the base body, display windows which arearranged radially around the axis, and an illumination device forilluminating at least one of the display windows. In addition, theinvention relates to a method for determining the rotary position of arotatable operator control element.

An operator control element of the type described at the beginning isknown, for example, from DE 101 27 211. Such operator control elementsare used, for example, in operator control units for motor vehicleair-conditioning systems as rotary switches for setting the airdistribution or as rotary potentiometers for predefining a temperaturevalue. Display windows which characterize the set state by means ofsymbols which are provided are arranged around the rotatable handle. Sothat the symbols can be recognized even when operating the device atnight, a means of illuminating the display windows or one of the displaywindows which represents the set value is necessary. For this purpose,light sources are used in the form of light-emitting diodes andlightguides. The light-emitting diodes which are used to illuminate thesymbols are actuated by a microcontroller of the operator control partin order to control the brightness of the display or switch it on/off.When the operator control elements are used in motor vehicles, a highdegree of precision in the supplied state is required or it is necessaryto perform standardization, for example on potentiometers.

The object of the invention is therefore to specify an operator controlelement for motor vehicles with which the position of the handle, andthus the set value on the control unit, can reliably and easily berecognized. A further object of the invention is to specify a reliablemethod for determining the rotary position of a rotatable operatorcontrol element.

The aforementioned object is achieved with an operator control elementof the generic type for motor vehicles in that the illumination devicehas a plurality of light sources which are arranged radially around theaxis of the handle on the fixed base body and can be switchedindividually, a lightguide element is permanently connected to thehandle and has a light input face, which is successively moved past thelight sources when the handle rotates, and a light output face, which isassigned to a photosensitive element, and the photosensitive element isconnected to an electronic circuit for evaluating the output signal ofthe photosensitive element, it being possible to determine a rotaryposition of the handle by successively switching the light sources andevaluating the output signal of the photosensitive element.

The operator control element according to the invention thus firstly hasa plurality of light sources which are arranged radially and preferablyat the same angular interval from one another around the axis of thehandle on the fixed base body of the operator control element. Alightguide element whose light input face is successively moved past thelight sources when the handle rotates is permanently connected to thehandle. With this configuration, light from in each case one of thelight sources is input into the light input face of the lightguideelement. The light which is input in this way is fed to a photosensitiveelement via the lightguide element. The photosensitive element isconnected to an electronic circuit which evaluates the output signal ofthe photosensitive element. The electronic circuit also serves toactuate the individual light sources. If the individual light sourcesare then briefly, for example only for a few milliseconds, switched onin succession, a corresponding signal is generated by means of thephotosensitive element if the light source which is assigned to thecurrent position of the handle, and thus of the photosensitive element,is switched on. This is evaluated in the electronic circuit so that theposition of the handle, and thus the setting value, can be unambiguouslydetected.

A method according to the invention for determining the rotary positionof a rotatable operator control element in which a plurality of lightsources are arranged radially around an axis of the operator controlelement, light from one of the light sources being fed to aphotosensitive element as a function of the rotary position of theoperator control element, therefore has the following method steps:

-   -   the light sources are switched on and off successively,    -   the signal of the photosensitive element which is detected        during the successive switching on and off of the light sources        is evaluated in order to generate a signal sequence,    -   the signal sequence which is obtained in this way is compared        with stored signal sequences to which a position value has been        assigned,    -   when the signal sequence which is determined corresponds to a        stored signal sequence, the associated position value is further        processed as a setting value of a motor vehicle component.

If all the light sources are firstly switched off and then brieflyswitched on in succession, the signal sequence is composed only of asingle signal value whose position depends on the set rotary angle. Ifthe operator control element has, for example, twelve light sources andthe lightguide element is positioned over the third light source, thesignal sequence is firstly composed of the signal value “no light”twice, then of the signal value “light” once, and subsequently in turnof the signal value “no light” nine times. It is analogous if the lightsources are all switched on, for example when the device is operating atnight. The light sources are then successively switched off so that thefollowing signal sequence is obtained in a way which is analogous to theabove example. Firstly, the output signal “light” twice, as thelightguide is positioned above the third light source and only the firstand second light sources are switched off. Then, as a third signal, “nolight” as the light source above which the lightguide element ispositioned is then switched off briefly and finally in turn the signal“light” nine times if the remaining nine light sources are switched off,but said light sources do not irradiate into the lightguide.

In the operator control element according to the invention, the lightsources can be used in particular both for detecting the position of thehandle, as has been described before, and directly for illuminating theindividual display windows. For this purpose, the lightguide element isto be constructed and arranged in such a way that it covers only a partof the output face of each light source so that the remaining part ofthe light from the light source can be used to illuminate the displaywindow. The latter can also take place in particular by means oflightguides.

In one particular embodiment, the photosensitive element is arranged ona printed circuit board which is a component of the base body, theprinted circuit board extending perpendicularly to the axis of theoperator control element. As a result, a particularly simple voltagesupply of the photosensitive element or a particularly simple connectionof the photosensitive element to the electronic circuit is possible.

In one particular embodiment, the photosensitive element is arranged inthe axis of the handle. In this embodiment, a single photosensitiveelement is sufficient and the lightguide element can be of particularlysimple design.

However, the operator control element can also have a plurality ofphotosensitive elements. In particular, with such a configuration it ispossible to reduce the number of necessary light sources. If, forexample, two photosensitive elements are provided and two lightguideelements or two branches of a lightguide element whose output faces areeach assigned to one of the photo-sensitive elements, the two inputareas, spatially separated from one another, of the two lightguideelements can detect different positions of the handle. For example,adjacent rotary positions A, B may be equipped with a light source or bewithout one. The light input face of the first lightguide element islocated in a first rotary position above the light source in theposition A, while the light input face of the second lightguide islocated above the position B, which does not contain any light source.The light which is input into the first lightguide is then fed to thefirst photosensitive element. In a second rotary position, the secondlightguide element is then located above the position A so that light isinput into the second lightguide element and thus into the secondphotosensitive element. In this way, it is possible to distinguishbetween the two rotary positions with just one light source.

In one particular embodiment, the operator control element is embodiedas a rotary switch. For this purpose, the operator control element haslatching elements which define the individual rotary positions in whichthe light input face of the lightguide element is assigned to preciselyone light source. The operator control element can be used here eitheras an absolute position sensor or as an incremental sensor fordetermining a relative position. In the latter case, during theadjustment process, the direction of rotation and the number ofincrements can be determined by suitably actuating the light-emittingdiodes, for example before the rotating process and after the completionof the rotating process, by correspondingly actuating the light sourcesand evaluating the photo-sensitive signal.

In particular, the operator control element is suitable as a componentof an operator control unit for a motor vehicle air-conditioning systemand for supplying a setting value for the control unit of theair-conditioning system. The operator control element in the form of anabsolute position sensor can be used here as an air distributionactuator or as a temperature selector. In the latter case, in particularfurther colored light sources, such as a red and a blue LED, may bepresent, with which light sources a minimum and a maximum temperaturevalue are characterized.

The invention is explained in more detail below with reference to anexemplary embodiment and the drawing, in which:

FIG. 1 shows a basic sectional view of the operator control elementaccording to the invention,

FIG. 2 shows a plan view of the operator control element.

FIG. 1 shows a sectional view of an operator control element accordingto the invention. The operator control element has a fixed base body 1.A handle 3 is mounted so as to be capable of rotating about the basebody 1 about an axis 2 by means of the schematically illustrated bearingelements 4. A lightguide element 5, which is embodied here as arod-shaped lightguide, but may also be merely composed of mirroredsurfaces, is permanently connected to the handle 2. The component of thebase body 1 is a printed circuit board 6 on which a plurality of lightsources 7 are arranged in a ring around the axis 2. The light source 7 bis switched on as a single light source in the example shown. The lightof the light source 7 b is input into the light element 5 and guided tothe photosensitive element 8 which is also arranged on the printedcircuit board 6. The photosensitive element 8 may be, in particular, aphotodiode or a phototransistor. The photosensitive element 8 isarranged on the axis 2 of the handle 3. At the same time, the outputface (not illustrated in more detail) of the lightguide element 5 isalso arranged on the axis 2 so that, when the handle 3 rotates, thearrangement of the light output face of the lightguide element 5 withrespect to the photosensitive element 8 is always ensured. Furthermore,an electronic circuit 9 is arranged on the printed circuit board 6. Theelectronic circuit 9 is electrically connected to the photosensitiveelement 8 and evaluates the signals of the photosensitive element 8.Furthermore, the electronic circuit 9 is connected to the individuallight sources 7 and supplies actuation signals for switching the lightsources 7 on and off. In the fixed base body 1 of the operator controlelement there are also a plurality of display windows 10 which are alsoarranged on a circular ring around the axis 2. The number of displaywindows 10 corresponds to the number of light sources 7. The arrangementof the lightguide element 5, of the light source 7 b and of the displaywindow 10 b is such that part of the light emitted by the light source 7b is input into the lightguide 5 in a corresponding rotary position ofthe handle 3. At the same time, part of the light of the light source 7b is used to illuminate the display window 10 b. This can ensure thatthe display window 10 b is illuminated when the device is operated atnight. The same applies to the other light sources and the associateddisplay windows. However, the lightguide element 5 only ever inputslight from one of the light sources 7 into the photosensitive element 8.

FIG. 2 shows a plan view of the operator control element with the fixedbase body 1 and the handle 3. In the exemplary embodiment shown, twelvedisplay windows 10 are arranged in the form of a circular ring aroundthe handle 3 in the base body 1. One of the light-emitting diodes 7 islocated underneath each of the display windows 10. The operator controlelement also has latching elements (not illustrated) which ensure thatonly one of the twelve possible settings can be made. The handle 3contains a marker 11 by means of which the current position of theoperator control element is signaled to the user.

The position of the operator control element according to the inventioncan then be detected as follows: the light sources 7 which are initiallyswitched off are briefly switched on in succession. If, in the process,a change in brightness is detected by the photosensor, it is possible todetermine which of the light sources has just been switched on when thedetected change in brightness took place. The position of the lightguideelement which must be located above the corresponding light source, andthe position of the handle, are thus known. An input value whichcorresponds to this position can then be passed on to the control unitof the air-conditioning device. The control unit of the air-conditioningsystem may in particular also be implemented on the printed circuitboard 6 in the form of the electronic circuit 9. In this case, theprinted circuit board 6 is not merely a component of a single operatorcontrol element but, for example, of a complete operator control unitwhich also already contains the control circuit.

1.-8. (canceled)
 9. An operator control element for motor vehicles, comprising: a fixed base body; a handle rotatably mounted on said base body for rotating about an axis, said base body having a plurality of windows arranged in circumferential succession about said axis; an illumination device for illuminating at least one of said plural windows, said illumination device including a plurality of light sources arranged on said base body in circumferential succession about said axis; a photosensitive element connected to an electronic circuit; and a lightguide element connected to said handle and having a light input face and a light output face, said light input face being moved past said light sources when said handle is rotated, and said light output face being assigned to face said photosensitive element for guiding light from one of said light sources aligned with said light input face to said photosensitive element, said electronic circuit being arranged and dimensioned for successively switching the light sources and determining a rotary position of the handle based on the output signal generated by said photosensitive element in response to the successive switching of said light sources.
 10. The operator control element of claim 9, wherein said one of said light sources aligned with said input face irradiates both into the input face and into one of said plural display windows.
 11. The operator control element of claim 9, further comprising a printed circuit board arranged in said base body and extending perpendicularly to said axis, said photosensitive element being arranged on said printed circuit board.
 12. The operator control element of claim 9, wherein said photosensitive element is arranged on said axis.
 13. The operator control element of claim 9, further comprising a plurality of photosensitive elements.
 14. The operator control element of claim 9, wherein said operator control element is a rotary switch.
 15. The operator control element of claim 9, wherein said operator control element is a component of an operator control unit for an air-conditioning system and supplies a setting value for a control unit of the air conditioning system.
 16. A method for determining a rotary position of a rotatable operator control element for a motor vehicle component, the rotatable operator control element having a plurality of light sources arranged in circumferential succession about an axis of the operator control element, wherein light irradiating from one of the plural light sources is fed to a photosensitive element as a function of the position of the operator control element, said method comprising the steps of: successively switching the light sources on and off; evaluating a signal output from the photosensitive element during the step of successively switching to generate a signal sequence; comparing the generated signal sequence to stored signal sequences assigned to respective position values; determining an associated one of the stored signal sequences that corresponds to the generated signal sequence; and processing the associated one of the stored signal sequences as a setting value of the motor vehicle component. 